Understanding the genomics involved in Parkinson’s disease development

Worried grey senior lady with walking cane in the garden with her son

Parkinson’s disease is a degenerative disorder of the nervous system which affects over 4 million people worldwide. It is caused when the brain cells responsible for the production of dopamine die. Dopamine is the chemical released by the brain to carry out body movements.

Role of genetics
About 15 % of Parkinson’s are linked to genetics. Interestingly, more than 15 genes have already been found to be linked to Parkinson’s.1 And out of that six genes are involved in pathogenesis. SNCA and LRRK2 genes are associated with the autosomal dominant form of Parkinson’s. The reason being, mutation in the single copy of these genes is a good enough reason to cause the disease. Here, the reason could be the mutated gene from one of his parents or a completely new mutation in the gene. For PRKN, PINK1, DJ-1 and ATP13A2 genes, the mutation is carried in both copies resulting in the autosomal recessive form of the Parkinson’s.

Role of ethnicity
Most of the time, much of our understanding of chronic disease comes from the clinical study of white patient groups. Although progress has been made in population-level genetics and molecular biology, a similar level of research has not been done keeping different ethnicities such as Asians in mind contributing to enduring health inequalities. This is because most of the research comes from the USA and Europe where mainly white subjects are studied. As a result, there are gaps in the findings associated with Parkinson’s disease.

As per several studies, it was found that the ethnic background determined the mortality rates. For example, Black patients had a higher incidence of death than White patients. On the other hand, Hispanic patients and some Asian patients had a lower rate of death than the White patients. However, all this research was based on the European and American population and hence the results cannot necessarily be applied to patients residing in India.

As per studies conducted in India, there were comparatively lower incidences of the disease. This was largely because most of the genetic mutations found to cause Parkinson’s disease in other populations was not found in India. But considering the huge number of Parkinson’s patients found in India in the elderly age group as well as of people under 40 years of age, it indicated factors other than ethnicity to play a role in the disease.

As a need to conduct more studies on the therapeutic aspects of the disease, certain pharma companies have taken the onus of conducting clinical trials for the latest new drugs in India, which are safinamide and apomorphine pump therapy.2 This apart, specific gene-based treatments targeting specific molecules in the cells are being experimented with to give better results for Parkinson’s patients. A case in point being an international study proposed to be conducted by the Michael J Fox Foundation for understanding the genetic pattern of Parkinson’s with possibly 10,000 patients from India. This is a huge step up considering that although this ageing-related disorder has good treatment options such as tablets, injections, pump therapies and surgeries, a cure has yet not been found for it.

Parkinson’s Disease Day is celebrated every year on April 11 and the theme this year is mental health. This is based on the challenge experienced by medical experts on patients with emotionally disturbed spells.